Motor and brush device

Abstract

A motor and a brush device are provided which allow an easy assembly of brush holders. The brush holders have fixing portions and brush accommodating portions integrally formed therewith. The fixing portions are secured to the gear case, and the brush accommodating portions slidably hold brushes. The motor has a gear case which is integrally formed with a reduction mechanism accommodating portion to accommodate a reduction mechanism and with a brush holder mounting portion in which the brush holders can be installed in a direction of an axis of the output shaft.

What is claimed is:  
     
         1 . A small motor comprising: 
 a motor case accommodating an armature, the armature being adapted to rotate when energized;    a rotatable reduction mechanism receiving the rotation of the armature;    an output shaft coupled to the reduction mechanism for rotation;    a gear case connected to the motor case to rotatably support the output shaft;    a brush electrically connectable to a commutator provided to the armature;    a brush spring for pressing the brush against the commutator; and    a brush holder installed in the gear case and slidably holding the brush;    wherein the brush holder has a fixing portion and a brush accommodating portion integrally formed therewith, the fixing portion being secured to the gear case, the brush accommodating portion slidably holding the brush;    wherein the gear case is integrally formed with a reduction mechanism accommodating portion for accommodating the reduction mechanism and with a brush holder mounting portion in which the brush holder can be installed in a direction of an axis of the output shaft.    
     
     
         2 . A motor according to  claim 1 , wherein the brush has a sliding portion and a tapered surface, the sliding portion being formed at almost a central part of the brush and protruding from a brush body to come into sliding contact with the commutator, the tapered surface adjoining the sliding portion and being arranged in a tapered configuration and adapted to contact the commutator and thereby increase an area of the brush in contact with the commutator as the wear of the sliding portion proceeds.  
     
     
         3 . A motor according to  claim 1  or  2 , wherein a pair of the brush and the brush accommodating portion has a temporary locking means which, when inserting the commutator, temporarily locks the brush at a predetermined position so that the commutator can be inserted and which, after the commutator has been inserted, unlocks the brush allowing the brush to come into electrical contact with the commutator.  
     
     
         4 . A motor according to  claim 3 , wherein the temporary locking means comprises a locking portion formed in the brush and a brush locking tongue piece formed in a part of the brush accommodating portion, the brush locking tongue piece being adapted to engage the locking portion of the brush when the commutator is inserted and, after the commutator has been inserted, to disengage from the locking portion.  
     
     
         5 . A brush device comprising: 
 a brush electrically connectable to a commutator provided to an armature of a motor; and    a brush holder secured to a case of the motor to hold the brush in such a way that the brush can be brought into sliding contact with the commutator;    wherein the brush is formed with a sliding portion and a tapered surface, the sliding portion protruding from a brush body to come into sliding contact with the commutator, the tapered surface adjoining the sliding portion and being arranged in a tapered configuration and adapted to contact the commutator and thereby increase an area of the brush in contact with the commutator as the wear of the sliding portion proceeds.    
     
     
         6 . A brush device according to  claim 5 , wherein the tapered surface of the brush comprises first and second tapered surfaces arranged one on each side of the sliding portion formed at almost a center of the brush with respect to a direction of rotation of the commutator.  
     
     
         7 . A brush device according to  claim 5  or  6 , wherein the sliding portion of the brush has a curved surface.  
     
     
         8 . A brush device according to  claim 5 ,  6  or  7 , wherein a pair of the brush and the brush accommodating portion has a temporary locking means which, when inserting the commutator, temporarily locks the brush at a predetermined position so that the commutator can be inserted and which, after the commutator has been inserted, unlocks the brush allowing the brush to come into electrical contact with the commutator.  
     
     
         9 . A brush device according to  claim 8 , wherein the temporary locking means comprises a locking portion formed in the brush and a brush locking tongue piece formed in a part of the brush accommodating portion, the brush locking tongue piece being adapted to engage the locking portion of the brush when the commutator is inserted and, after the commutator has been inserted, to disengage from the locking portion.